Free Online Inflation Impact Calculator

What the inflation impact calculator shows

This inflation impact calculator shows how inflation erodes the purchasing power of money over time, and how an investment return can offset that loss. You enter an amount, an expected yearly inflation rate, an expected yearly return and a number of years. The calculator answers two questions in today's money: how much will this sum be able to buy in the future if it sits idle, and what would it be worth, after inflation, if it were invested instead.

It is a forward-looking inflation calculator. Many inflation calculators answer the opposite question, such as what $100 from 1990 is worth today, using official price index data for past years. This tool does not look anything up. It applies the rate you choose to the years ahead, which makes it useful for questions such as:

• How much will $10,000 be worth in 20 years at 3% inflation?
• What return do my savings need just to keep their purchasing power?
• How much buying power does a retirement fund lose before I start spending it?

Everything runs in your browser, and nothing you enter is sent anywhere.

In this guide:

• How to fill in each field and read the results, the chart and the table
• The exact formulas behind the numbers, and what the calculator leaves out
• What inflation is, how the Consumer Price Index measures it, and recent US figures
• Purchasing power, the real rate of return, and the rule of 70
• Reference tables, three worked examples in US dollars, and common mistakes

If the idea of money losing value is new, start with the basics article on inflation and why money loses value.

How to use the inflation impact calculator

The calculator opens in US dollars with an amount of $10,000, 12% inflation, a return of 8% and 10 years. The UAH / USD / EUR switch sits in the Your numbers header on wide screens and under More options on phones; it only changes the symbol. Each input has a number box and a slider:

1. Current amount. The sum you want to follow, in today's money.
2. Annual inflation rate. The yearly rise in prices you expect, in percent. The High, Moderate and Low chips under the slider set 12%, 5% or 2%.
3. Annual investment return. The yearly return you expect on the money, in percent, before inflation.
4. Time horizon. The number of whole years to project.

The rate sliders move in steps of 0.5, but you can type 3.7. Values outside a range are pulled back to its limit, and the time horizon is rounded to whole years. On phones, the amount has − and + buttons.

Reading the results

All results are in today's money at the end of the time horizon. The headline, Purchasing power after N years, is what the current amount will be able to buy if it stays as cash, earning nothing. A bar splits the current amount into that purchasing power and the part inflation takes. Three figures follow:

• Purchasing power lost is the current amount minus the purchasing power.
• Value if invested is what the amount would be worth after earning the investment return every year, converted back into today's money.
• Real gain vs. inflation is the value if invested minus the current amount. It is negative when the return is below inflation.

The Chart tab draws the dotted nominal amount, which stays flat because a banknote keeps its face value, the shrinking purchasing power and the value if invested. The Year by year tab lists them for every year.

Pin to compare keeps the current scenario: after pinning the defaults and clicking Moderate, the headline shows +$2,919 vs pinned, and the chart a dashed line. Switching the currency, Reset or a reload clears it. PDF exports the inputs, the four results and the yearly table. On phones and tablets, the results sit in a bar at the bottom of the screen; Details opens the rest.

How the inflation calculation works

The calculator applies inflation and the investment return once a year, at the end of each year, and expresses every result in the purchasing power of today.

Purchasing power

Inflation compounds: each year's price rise applies to prices that have already risen. To find what an amount will be able to buy after a number of years, the calculator divides it by the cumulative price factor:

Purchasing power = A ÷ (1 + π)^t
Purchasing power lost = A − Purchasing power

• A is the current amount
• π is the annual inflation rate as a decimal (3% is 0.03)
• t is the year, from 1 to the time horizon

At 3% inflation, $10,000 divided by 1.03 to the tenth power is $7,441. The loss after one year is a little smaller than the inflation rate: at 3.7% inflation, $10,000 keeps the purchasing power of $9,643, a loss of $357, not $370, because the divisor is 1.037.

Value if invested

For the investment, the calculator combines the return and inflation in one yearly growth factor:

Value if invested = A × ((1 + r) ÷ (1 + π))^t
Real gain = Value if invested − A

• r is the annual investment return as a decimal

The fraction in the middle is one plus the real rate of return, so this is the same as growing the amount at the nominal return and then dividing by the price factor. The result is in today's money. The dollar balance the account itself would hold is never shown. If you need it, multiply the value if invested by (1 + π)^t, or use the compound interest calculator with the same return.

When the return equals inflation, the factor is exactly 1 and the value if invested stays at the current amount. When the return is lower, the value shrinks, only more slowly than idle cash.

Assumptions behind the numbers

• One lump sum. No monthly saving, no withdrawals and no spending along the way.
• Constant rates. The inflation rate and the return are the same in every year. There is no volatility, no losing year and no change in rates.
• Annual compounding for both inflation and the return, applied at the end of each year.
• No deflation and no negative returns. Both rate fields start at 0%.
• Not modelled: taxes on interest or gains, fund fees, transaction costs and exchange rates. Enter a return that is already net of fees if you want them included, and remember that taxes would reduce it further.
• One price level. The rate applies to everything you buy. Your own costs may rise faster or slower than the average.

The results are scenarios at the rates you choose, not forecasts.

What inflation is and how it is measured

Inflation is a sustained rise in the general level of prices. When it happens, each unit of money buys less than before. Deflation is the opposite, a general fall in prices, and it is rare in modern economies.

In the United States, the most widely quoted measure is the Consumer Price Index (CPI) from the Bureau of Labor Statistics. The BLS describes the CPI as a measure of the average change over time in the prices paid by consumers for a representative basket of goods and services. Its main version, the CPI for All Urban Consumers (CPI-U), covers more than 90% of the US population and is published every month. The BLS also notes that the CPI is used as a deflator to find the purchasing power of the consumer's dollar, which is exactly the calculation this tool repeats into the future.

The September 2026 CPI release, published on October 14, 2026, reported that the CPI-U rose 3.7% over the previous 12 months before seasonal adjustment. Excluding food and energy, the so-called core index rose 2.6%. The next release is scheduled for November 10, 2026.

The Federal Reserve sets its goal with a different measure. Its Federal Open Market Committee judges that inflation of 2 percent over the longer run, measured by the annual change in the price index for personal consumption expenditures (PCE), is most consistent with its mandate. The 2% goal is the reason the Low preset uses 2%.

Recent years show how much the rate can vary. These are annual averages of the CPI-U, all items, from the BLS summary of annual indexes:

The rate you enter in the calculator is an assumption about the future average, not a measured fact. A single year's figure, high or low, is rarely a good guess for the next 20 years.

Purchasing power: what your money will buy in the future

Purchasing power is what a sum of money can actually buy. The number on a bank statement is the nominal amount. Its purchasing power is that amount divided by how much prices have risen. The calculator shows both: the flat dotted line is the nominal amount and the falling line is its purchasing power.

There are two ways to describe the same effect. Looking at prices, something that costs $100 today costs $134 after 10 years and $243 after 30 years at 3% inflation. Looking at money, $100 today buys what $74 would buy in 10 years and what $41 would buy in 30. The price figures are computed for this guide as 100 × (1.03)^t. The calculator itself always uses the second view, converting the future back into today's money.

The table shows the second view for common amounts at 3% inflation, using the calculator:

The percentage loss does not depend on the amount. After 30 years at 3%, any sum has lost 58.8% of its purchasing power. That is why a retirement target set in today's dollars needs to grow just to stand still, and why the investment goal calculator and the FIRE calculator are best used with real, inflation-adjusted returns.

The loss also accelerates with the rate, not in proportion to it. Over 30 years, 2% inflation removes 44.8% of purchasing power, 4% removes 69.2% and 10% removes 94.3%.

Real rate of return: nominal vs real

A nominal return is the growth of a balance in dollars. The real rate of return is the growth in what that balance can buy. They are linked by the Fisher relationship, which is the formula the calculator uses:

real rate = (1 + nominal rate) ÷ (1 + inflation) − 1

The popular shortcut is nominal minus inflation. It is close at low rates and drifts further off as rates rise, because it ignores the fact that inflation also erodes the return itself. The table compares both over 20 years for $10,000. The 20-year value comes from the calculator; the exact real rate, which it does not display, follows the Fisher formula above. The shortcut column applies nominal minus inflation for 20 years and is computed for this guide.

Three rows show why the exact version matters. At 5% and 3%, and at 12% and 10%, the shortcut gives the same 2%, yet the exact real rates are 1.94% and 1.82%. In high-inflation settings the shortcut overstates the real return by a meaningful amount: at 20% and 15% it adds more than $3,000 to a 20-year result on $10,000. When the return is below inflation, the shortcut exaggerates the loss instead.

A real rate of zero is the line between gaining and losing purchasing power. In the calculator, it is the point where the value if invested equals the current amount and the real gain is $0. The risk and return article explains why investments with higher expected real returns also come with a wider range of outcomes.

The rule of 70: how fast inflation halves your money

The rule of 70 is a quick way to estimate how many years it takes for inflation to cut purchasing power in half: divide 70 by the inflation rate in percent.

years to halve ≈ 70 ÷ inflation rate in percent
exact years = ln 2 ÷ ln(1 + π)

The rule of 72, better known for doubling money, gives the same kind of estimate and is slightly more accurate at higher rates. The table compares both with the exact figure, computed for this guide, and checks the result in the calculator with $10,000 and the nearest whole number of years:

Both rules are within a few months of the exact answer for the rates most people use. The point of the rule is not precision but intuition: at 2% inflation, money held as cash loses half its value over a typical working life; at 7%, it takes about a decade. The same arithmetic works in reverse for growth, which the article on compound interest and the time value of money covers in detail.

How inflation affects savings

Inflation hurts savings whenever the interest earned is lower than the rate at which prices rise. The balance grows in dollars, so nothing looks wrong on the statement, yet each year it buys a little less. This is why inflation is sometimes called a hidden tax.

Here is $10,000 over 10 years at 3% inflation, with different yearly returns, as the calculator shows it:

A return below inflation does not protect purchasing power; it only slows the loss. At 2% a year, the account ends almost $1,000 short of today's buying power.

Taxes raise the bar

The calculator does not apply tax, but interest on savings is usually taxable. If tax takes a share t of each year's interest, the pre-tax rate needed just to match inflation is roughly inflation ÷ (1 − t). These figures are computed for this guide and are illustrative, not any person's tax rate:

To include tax in a calculator run, enter the after-tax return in the Annual investment return field. The deposit vs investment calculator models tax and fees directly.

Where people keep money when inflation is high

There is no instrument that protects against inflation in every situation, but some are built for it. Two US Treasury products are linked to the CPI:

• Treasury Inflation-Protected Securities (TIPS). TreasuryDirect explains that the principal of TIPS rises with inflation and falls with deflation, interest is paid every six months at a fixed rate on the adjusted principal, and at maturity you receive the greater of the adjusted or the original principal. They are sold in 5-, 10- and 30-year terms.
• Series I savings bonds. The rate combines a fixed rate and an inflation rate that resets every six months. For I bonds issued from May 1 to October 31, 2026, the overall rate is 4.26%, with a fixed rate of 0.90%. They can be cashed after 12 months, cashing before 5 years costs the last 3 months of interest, and one person can buy up to $10,000 in electronic I bonds per calendar year. Interest is subject to federal income tax but not state or local income tax.

Savings accounts and CDs keep their dollar value but may or may not beat inflation, depending on the rate. Stocks and stock funds have historically been one way to outpace inflation over long periods, but they can lose value, sometimes for years. The types of investment assets article compares the main options, and the article on bonds explains how fixed interest payments are affected when inflation rises. Short-term and emergency money is usually kept safe and accessible first, as the emergency fund article explains.

Historical US inflation vs this projection

Search for an inflation calculator and you will often find historical lookups: what a dollar from 1980 is worth today. This tool projects a constant rate forward instead, so the two answer different questions. They connect in one useful way: the past can suggest a reasonable rate to enter.

To find the average yearly inflation between two years, divide the later CPI by the earlier one and take the root for the number of years. The averages below are computed for this guide from BLS CPI-U annual averages (the historical CPI-U table for years to 2015 and the annual summary for later years). The last column enters the rounded average into the calculator for $10,000 over the same number of years:

Two lessons stand out. First, a few percent a year adds up: average prices in 2025 were almost six times their 1975 level, so $10,000 kept as cash from 1975 to 2025 would buy what about $1,671 bought in 1975, using the index ratio directly. Second, averages hide swings. In 1979 and 1980, average prices rose 11.3% and 13.5%, while 2015 saw just 0.1%. A constant-rate projection smooths all of that away.

To convert a past amount exactly, multiply it by the ratio of the two index values, or use the CPI inflation calculator. To look forward, use a range of rates in this calculator rather than a single number.

Inflation impact at a glance

This grid shows the purchasing power of $10,000 in today's money after each period at a constant inflation rate, with the money held as cash. Every value comes from the calculator. The amounts scale with the sum, so $50,000 gives five times these figures.

To read the value if invested from this grid, find the row for your real rate of return instead of inflation, and treat it as growth: a real return of 2% for 20 years multiplies the amount by 10,000 ÷ 6,730, about 1.49. The calculator does this for you.

Worked examples

Each example uses USD as the display currency and shows what the calculator returns for the inputs listed.

Common mistakes when estimating inflation impact

• Reading the value if invested as a dollar balance. It is already converted into today's money. The account itself would show a larger number.
• Using the shortcut nominal minus inflation at high rates. The calculator uses the exact formula. At 20% and 15%, the shortcut overstates the real return by about 0.65 points a year.
• Taking last year's inflation as the long-run rate. A single year can be far from the average. Try a low, a middle and a high rate and look at the range.
• Forgetting the currency. The calculator opens in US dollars. Switch to EUR or UAH as needed; nothing is converted either way.
• Mixing currencies and inflation rates. Use the inflation rate of the currency you hold. Dollar savings follow US inflation, not the inflation of the country you live in, although exchange rates matter if you spend in another currency.
• Ignoring taxes and fees. The return field is used as entered. Enter a return after fund fees and, if you want, after tax; otherwise the real gain is overstated. The fees drag calculator shows how fees compound.
• Treating a steady return as guaranteed. Investments can lose money in any year. A constant return shows the long-run arithmetic, not the path.
• Assuming your costs follow the CPI. The index is an average basket. Rent, health care or tuition may rise faster for you.

Limitations and next steps

The inflation impact calculator answers one question clearly: at a constant inflation rate and a constant return, what a lump sum will be worth in today's money after a number of years. It does not know future inflation, your own spending basket, your taxes or what markets will do. It cannot model regular saving, withdrawals, changing rates, deflation or a losing year, and it does not show past inflation for specific years.

Use it to see the size of the effect, then look at the parts it leaves out:

• The compound interest calculator adds monthly contributions and shows nominal balances.
• The deposit vs investment calculator compares a savings account with an investment after tax and fees, in both nominal and real terms.
• The investment goal calculator works out how much to save for a target, which you can set in today's dollars.
• The emergency fund calculator sizes the cash you keep safe before investing.
• The CPI inflation calculator converts past amounts with official monthly price indices.

For background, read about inflation and why money loses value and what investing is. For decisions about your own savings, taxes or retirement, consider a qualified, independent financial adviser who can take your full situation into account.